Adding part to dummy?

How do you attach parts to a player’s humanoid? Like this:

However, I’m getting this:

Is the Part Welded to the Dummy’s HumanoidRootPart?
Is this Dummy an NPC or is it Anchored?
How are you trying to do it? Your second picture looks identical to your first without the transparent yellow ‘Part’ outline.

If you don’t give us more information we can’t help you.